The present invention relates generally to radio frequency identification (RFID) antennas, and more specifically related to RFID antennas installed on shelves.
A RFID system uses radio frequency transmission to identify, categorize, locate and track objects. The RFID system comprises two primary components: a transponder or the RFID tag and a reader. The tag is a device that generates electrical signals or pulses interpreted by the reader. The reader is a transmitter/receiver combination (transceiver) that activates and reads the identification signals from the transponder. In order to effectively transmit and receive radio frequency signals, the reader often includes suitable antennas. The RFID tags are attached to objects that need to be tracked, and can be programmed to broadcast a specific stream of data denoting the object's identity, such as serial and model numbers, price, inventory code and date. A reader will detect the “tagged” object and further connects to a large network that will send information on the objects to interested parties such as retailers and product manufacturers. The RFID tags are considered to be intelligent bar codes that can communicate with a networked system to track every object associated with a designated tag. Therefore, the RFID tags are expected to be widely used in wholesale, distribution and retail businesses.
It is of interest to communicate with RFID tags attached to merchandise (or containers) stored on shelves in a warehouse or retail establishment. With existing technology, this may be achieved in one of two ways: (1) a mobile RFID scanner that moves along the shelves, possibly hand-held, or (2) by mounting a large number of fixed scanners to cover all the shelves. The former approach is very time consuming and labor-intensive, while the latter approach is very complex and expensive. The latter approach is particularly challenging because a static system will experience regions of signal fading (i.e., multipath interference) which must be overcome by providing sufficient spatial and polarization diversities. Furthermore, in the case of having multiple fixed scanners or reader antennas, it is difficult to conceal these devices in an aesthetically pleasing manner.
In view of the above applications, there is clearly a need to develop a RFID shelf antenna that can cover a large section of the shelf system without increasing the level of complexity and cost for the RFID system.